The present invention relates to a thermoelectric measuring method for analyzing physical properties or characteristics of a sample through measurement of the thermoelectricity flowing therethrugh, in particular, the thermoelectric measuring method for enabling the measurement of the physical properties of a powder, such as, toner for use in electrophotography, for example, with using such the thermoelectric measuring method under the desired atmosphere of water vapor, and it also relates to a thermoelectric measuring apparatus for making an analysis through measurement of the thermal stimulated current thereof, as well as, a thermoelectric measuring apparatus using thereof.
A method for analyzing the physical properties or characteristics of a material to be measured (i.e., a sample), through measurement of the thermal stimulated current (TSC) thereof, is already known, for example, in JIS (Japanese Industrial Standard), K7131, etc., as to be the thermoelectric measuring method for analyzing the physical characteristics of the sample through measuring the thermoelectricity. In such the already well-known analyzing method, such as, a testing method of thermal stimulated current of a plastic film, detection is made upon current of a femto-ampere order (fA=10−15A) or a pico-ampere order (pA) (this is, so-called the thermal stimulated current (TSC)), which flows in an external circuit putting a test piece or tip there between, when dielectric polarization and/or electric charges are released or discharge due to an increase of temperature thereof, which are frozen or trapped within the test tip of a dielectric substance or an insulating material, such as, plastics, for example, under low temperature (for example, −180° C.), thereby analyzing the physical characteristics of the materials.
In a measuring apparatus of using such the TSC method, as is known from the following Patent Document 1, a sample assembly includes wires, being pull out from an electrode contacting upon the surface of a sample and supported by a pair of supporting rods, and that assembly is so structured that it can be received within an inside of an electric furnace for use of an increase of temperature, around the outer periphery of which is wound with a heater coil. And, that assembly and the electric furnace are received within a container for building up the thermal insulation thereof and the electromagnetic shielding from an outside thereof. Further, this sample container has such the structure, that a space is provided for circulating liquid nitrogen, etc., or constant-temperature water therein, for example, within an inside of a vacuum chamber provided for heat-insulation from the outside, for bringing the inside thereof to be controllable at a desired temperature, and further to receive the assembly and the electric furnace within an inside thereof.
Also, a measuring method for measuring the charging with electricity or electrification characteristics is already known from the following Patent Document 2, of the toner for use of the electrophotography, being as the powder material, in particular, with using a method for analyzing the physical characteristics with an aid of the TSC method.
Thus, in this Patent Document 2 it is described that, after being weighted, a certain amount of the toner to be measured for use of electrophotography is mounted on an electrically conductive support (i.e., an electrode), and is suppressed by a plunger under the room temperature, thereby being formed into a disc-like shape through the pressure forming. Then, it is charged with electricity thereon by means of a corona electrifier, to be a toner sample. And then, this charged or electrified toner sample is introduced into the measuring apparatus, and current is detected from the opposing electrodes while increasing the temperature at a predetermined increasing rate or velocity with an aid of a thermo-couple, thereby enabling the composition and the physical characteristics of resin for the toner obtainable, as well as, a preparation of the toner, and further quantitative data being useful for studying the relationship between and the condition and the electrification characteristic thereof.
Patent Document 1: Japanese Patent Laying-Open No. 2002-071599 (2002); in particular FIG. 4 thereof; and
Patent Document 2: Japanese Patent Laying-Open No. Hei 8-62885 (1996); in particular FIGS. 5 and 6 thereof.
Also, relating to the Patent Document 2 mentioned above, the following Non-Patent Documents are already known:                Non-Patent Document 1: Kenji HORI, et al. “Thermally stimulated current spectra of powdered binder-resins for toner”, a paper of Japan Electrostatic Institute '94 (1994.8) pp. 247–250;        
Non-Patent Document 2: Osamu TAKAHASHI, et al. “Emission of Charged Particles by Friction and Its Effect on Frictional Charging”, a magazine of Japan Electrostatic Institute, 20, 4 (1996) pp. 252–254;
Non-Patent Document 3: Kazuo IKEZAKI, et al. “Fundamental Electric Properties of Powder-Formed Material”, a magazine of Japan Electrostatic Institute, 22, 2 (1998) pp. 79–82;
Non-Patent Document 4: Ronji KUWABARA, et al. “Thermal shrinkage effect of power-formed polymers on their thermally stimulating current spectra”, a paper of Japan Electrostatic Institute, '00 (2000.9) pp. 229–232;
Non-Patent Document 5: Tatunori HASHMOTO, et al. “Thermally Stimulated Current Spectra of Cryogenically Pulverized Polypropylene”, a paper of Japan Electrostatic Institute, '01 (2001.9) pp. 111–114; and
Non-Patent Document 6: Keiki SUGANAMI, et al. “Configuration of CCA Particles in the Toner Surface and Its Influence on Charging Characteristics”, a magazine of Society of Powder Technology, Japan, 39, pp. 642–647 (2002).
By the way, with such the measurement and the apparatus of using the TSC method therein, relating to the conventional arts mentioned above, in general, a sample to be measured is charged with electricity by means of a corona electrifier, for example, and it is measured within a helium gas or an air (i.e., the atmosphere). In case of a helium gas, it contains no water vapor therein, and in case of an air, it depends upon the condition (i.e., the humidity) of the atmosphere at that time. Namely, with the conventional art, it is impossible to make measurement upon the sample to be measured under an atmosphere adjusted in the humidity thereof.
However, in particular, for a powder sample, such as, the toner for use in the electrophotography or the like, for example, known from the Patent Document 2 mentioned above, sometimes it is necessary to make the measurement thereon, within an atmosphere of a desired humidity (e.g., water vapor). For example, the performances of the toner for use in the electrophotography are determined upon an amount of electric charge or electrification thereon, however this amount of electric charge is further influenced upon the temperature and the humidity, largely. Also, for the purpose of measuring the toner for use in the electrophotography under the condition near to the actual use situation thereof, there is required a method for measuring the thermoelectricity, enabling the measurement thereof even within the atmosphere of humidity (or water vapor), and further an apparatus for measuring the thermoelectricity for it.